A group of 130 business leaders have insisted that the case for Scottish independence "has not been made".

Company chiefs have signed an open letter highlighting the "uncertainties" that surround leaving the UK as they argue that "by continuing to all work together we can keep Scotland flourishing".

The group includes Weir Group chief executive Keith Cochrane, Angus Cockburn, interim chief executive of Aggreko, and Victor Chavez of Thales UK.

Audrey Baxter, of Baxters Food Group, and Boyd Tunnock are also among the signatories.

Mr Cochrane insisted businesses north of the border would face additional costs if there is a Yes vote on September 18.

He told BBC Radio Scotland's Good Morning Scotland: "It's clear to me and the 130 business leaders that have signed this letter from all shapes and sizes of business that there will be additional costs.

"We all want Scotland to be successful. Scotland is successful today, with many successful businesses, and we believe that working within the framework of the United Kingdom is the best way to secure that for the future."

Paul Fletcher of the pro-independence group Business for Scotland argued it was possible borrowing costs could be lower north of the border than the rest of the UK because of the strong performance of the country's economy.

"The cost of borrowing in Scotland may even be lower than the rest of the UK," he told the same programme.

All the business leaders that have signed the letter have done so in a personal capacity, stating: " As job creators, we have looked carefully at the arguments made by both sides of the debate.

"Our conclusion is that the business case for independence has not been made.

"Uncertainty surrounds a number of vital issues including currency, regulation, tax, pensions, EU membership and support for our exports around the world; and uncertainty is bad for business."

Listed as signatories are The Co-operative Bank chief executive Niall Booker, Ian Curle of Famous Grouse producer The Edrington Group and Douglas Flint, group chairman of HSBC Holdings, along with Peter Gordon, director of William Grant & Sons Distillers, and Cairn Energy chief executive Simon Thomson.

The group said "much is at stake" when the Scottish electorate votes in the independence referendum in just over three weeks.

It said: " Our economic ties inside the United Kingdom are very close and support almost one million Scottish jobs. The rest of the UK is Scotland's biggest market by far.

"Today, Scotland's economy is growing. We are attracting record investment and the employment rate is high.

"We should be proud that Scotland is a great place to build businesses and create jobs - success that has been achieved as an integral part of the United Kingdom."

Mr Cochrane said: "We felt it was important that Scottish business contributes to the debate, these are real businesses accounting for real jobs and expressing their person views that the business case has not been made for independence."

He argued it was " clear that irrespective of the currency option that is adopted there will be additional costs for Scottish business - higher interest rates, additional borrowing costs, and that impinges on the cost competitiveness of us".

Mr Cochrane, whose Weir Group has already spoken out against independence, said: " The facts demonstrate that under any option Scottish interest rates would be higher because of the lack of liquidity in terms of Scottish debt, the lack of a track record in terms of borrowing.

"There will clearly be additional costs to Scottish business and we're concerned that will impact our cost competitiveness for the long-term."

While Mr Fletcher said he could not guarantee an independent Scotland would not face higher interest rates, he added that credit ratings agencies had "suggested Scotland would attract their highest credit rating, so the cost of borrowing in Scotland may even be lower than the rest of the UK because our economy outperforms".

He also stated it was " very clear we will have the pound post September 18".

Mr Fletcher said: " There's some fantastic businesses on this list, it's a shame they don't see change and opportunity as a fantastic thing, potentially the most important thing.

"It's also a shame that they underestimate the role of their highly qualified, non-transitory workforces or really the role that Scotland has played in building up their brands."

He stated there were risks involved in staying part of the UK, highlighting Conservative plans for a referendum on European Union (EU) membership.

Mr Fletcher said: " There's risks in staying in the UK - will the UK for example be part of the EU, which is a far bigger market than all of the UK?"